1. Field of the Invention
This invention relates generally to portable air deflectors, and more particularly to a collapsible portable air deflector apparatus securable to the roof of an automobile for deflecting air streams away from a trailing vehicle.
2. Description of the Prior Art
Air flow deflection apparatus for motor vehicles for diverting air streams away from the leading blunt surface of a trailing vehicle are generally known in the art. Such air flow deflection apparatus can be generally classified into three major classifications, according to the manner and place of attachment and to the use to which the particular air deflector apparatus is put.
A first general classification includes those air deflectors which are permanently secured to or form an integral part of the towing vehicle. The air deflectors within this classification are typically secured to the cab of a tractor-trailer combination for deflecting air currents away from the front surface of the trailer in tow by the tractor. The air deflectors in this classification generally comprise solid, specially molded configurations which are particularly adapted for permanent affixation either directly to the tractor's roof or to the rear surface of the tractor's cab with an upper deflector portion extending above the general plane of the cab roof. These devices are typically sized for special fitting to the cab with which they are to be employed, are generally non-portable heavy/bulky devices which are designed for continuous use with a particular tractor cab and are not designed with the intent of ease of removal from the cab.
Within the last decade, the increased enthusiasm for camping and the use of towable camping vehicles has created another major application for air flow deflectors within the recreational and sports arena. In most recent years, the energy crisis, and particularly with respect to shortages of petroleum products, has placed increased emphasis on the conservation of petroleum used for mobilizing recreational vehicles. Such considerations have been prime factors involved in the development of low profile or vertically collapsible camping trailers. The drag factor attributable to wind resistance against the front surface of a vehicle in tow can be many cases produce an increase in gasoline consumption by the towing vehicle of greater than 50%. Besides the increased gasoline consumption, the engine of the towing vehicle is forced to work much harder over extended periods of time than those conditions for which it was designed, reducing engine life, further attributing to energy conversion inefficiences, and proportionately increasing the emission of pollutants into the air.
Accordingly, the second and third general prior art classifications of air deflectors apply to solving the air stream drag problems of towable vehicles such as mobile homes, recreational and camping trailers and the like. The second classification of air deflectors generally includes those air deflection apparatus which are physically secured to the leading surface of the detachable towed vehicle.
Since air deflectors within this classification are typically designed for use with that particular towed vehicle with which they are to be employed, the design of these deflectors generally varies to suit the size and shape of the towed vehicle. These devices are generally bulky and non-portable and are shaped to form an integral part of the towed vehicle or as a permanent fixture thereof. Further, their effectiveness in diverting the main air stream away from the forward surface of the towed vehicle is decreased since the encountered air stream must physically engage the towed vehicle itself before the deflection process occurs.
The third prior art general classification of air flow deflectors, include portable wind deflectors designed for removable attachment to the roof of a motor vehicle. Such deflectors, besides offering the versatility of deflecting air flow currents from a towed vehicle of any configuration, are theoretically designed for use with automobiles having varied roof configurations and sizes, and offer the advantage of continuing that air flow deflection initially provided by the automobile proper, out and away from the automobile such that these deflected air currents bypass the towed vehicle. This invention particularly applies to the type of air flow deflectors generally classified within this group, to which the following observations apply.
Since a portable air stream deflector for removable connection to a motor vehicle roof is generally employed for only relatively short periods of overall use of the vehicle, it becomes highly desirable to design the air deflector for ease of storage when not in use. However, the design criteria which serve to satisfy the ease of storage requirement generally run contra to those criteria required for maximizing the air stream deflection properties of the apparatus. For example, ease of storage dictates that flat, thin, collapsible and light-weight apparatus be employed; whereas maximization of air stream deflection dictates that a non-flat, plow, V-shaped or aerodynamically configured apparatus be employed. The prior art portable roof-top deflectors have not provided a design which optimizes both the deflection and the storage requirements of such a device.
Those prior art portable devices which have addressed the storage problem typically employ a single air deflecting member attached to the roof of a towing vehicle which is inclined rearwardly and upwardly from a position near the front edge of the roof to deflect the encountered air stream primarily above the front surface of the towed vehicle. Such devices generally require a relatively lengthy air deflector member of heavy construction to withstand the extreme air pressures applied thereto and also require rugged hold-down means to secure the deflector to the vehicles roof. Other prior art portable air deflectors use pairs of upright rectangular panels hinged together at one end and mounted to the roof of an automobile such that the hinge axis is perpendicular to the direction of travel of the vehicle. This type of apparatus, while offering some advantages of collapsability for ease of storage, provides air flow deflection primarily to the sides of the towed vehicle and requires heavy structural design for providing height adjustment of the deflection panels to correspond to the height of the trailer pulled by the automobile. This type of structure, by deflecting the air stream only to the sides of the vehicle also requires relatively heavy construction to withstand the severe air flow currents and lift forces to which it was subjected, and itself provides a measure of drag to the automobile.
To the contrary, those portable prior art air stream deflectors which employ aerodynamically contoured designs or contoured plow-shaped designs for simultaneously diverting the encountered air stream both over and to the sides of the towed vehicle, have been designed in rigid one-piece construction, generally by means of a molding process. Such prior art devices have been cumbersome to handle and difficult to store when not in use.
The present invention overcomes these disadvantages of the prior art, and provides an efficient air stream deflection apparatus for simultaneously deflecting an encountered air stream above and to the sides of the towed vehicle when in use, while collapsing to a compact, lightweight and easily storable configuration when not in use. While particular materials will be described in connection with the preferred embodiment of the invention, it will be understood that the invention is not limited to the use of these materials. Further, while the preferred embodiment uses a specific shape of deflector panels, it will be understood that other planar configurations could equally well be employed within the spirit and intent of this invention. Further, while specific tie-down strap configurations are described for mounting the preferred embodiment deflector apparatus to the roof top of a motor vehicle, it will be understood that other mounting configurations could equally well be employed within the spirit and intent of this invention.